Laundry treatment apparatus

ABSTRACT

A laundry treatment apparatus according to the present invention includes a casing; an outer tub disposed in the casing; a support rod connected at one end thereof to the casing; an outer tub support part, which is moved along the support rod and which supports the outer tub; at least one elastic member fixedly disposed on the support rod so as to elastically support the outer tub support part from below; a first friction part disposed above the outer tub support part so as to create frictional force between the support rod and the first friction part; and a housing defining therein a space for accommodating the first friction part, the housing being disposed at the top of the outer tub support part and being moved along with the outer tub support part when the outer tub vibrates, and the housing being independently moved alone when the outer tub support part is moved within a predetermined displacement range and being moved while pushing the first friction part when the outer tub support part is moved beyond the predetermined displacement range.

TECHNICAL FIELD

The present invention relates to a laundry treatment apparatus.

BACKGROUND ART

In general, a laundry treatment apparatus, which is an appliance thattreats clothes by applying physical and chemical action to the clothesusing water and detergent, includes a casing, and outer and inner tubsdisposed in the casing. The outer tub is disposed in the casing in asuspended manner, and the inner tub is rotatable in the outer tub.Vibrations resulting from the rotation of the inner tub have to beadequately controlled in view of the stability of the entire system.

In recent years, it has been required to increase the size of an inneror outer tub as large as possible, which results in an increase in thecapacity of treating clothes, while preventing an increase in the volumeof the entire washing machine, in response to the recent trend towardincreased washing capacity. To this end, the distance between the innertub and the outer tub and the distance between the outer tub and thecasing are increasingly reduced. Since collision between the componentsmay occur when vibrations are not sufficiently absorbed, there is anecessity to provide a solution to this problem.

DISCLOSURE Technical Problem

It is an object of the present invention to provide a laundry treatmentapparatus capable of more efficiently absorbing vibrations.

Technical Solution

A laundry treatment apparatus according to the present inventionincludes a casing; an outer tub disposed in the casing; a support rodconnected at one end thereof to the casing; an outer tub support part,which is moved along the support rod and which supports the outer tub;at least one elastic member fixedly disposed on the support rod so as toelastically support the outer tub support part from below; a firstfriction part disposed above the outer tub support part so as to createfrictional force between the support rod and the first friction part;and a housing defining therein a space for accommodating the firstfriction part, the housing being disposed at the top of the outer tubsupport part and being moved along with the outer tub support part whenthe outer tub vibrates, and the housing being independently moved alonewhen the outer tub support part is moved within a predetermineddisplacement range and being moved while pushing the first friction partwhen the outer tub support part is moved beyond the predetermineddisplacement range.

Advantageous Effects

The laundry treatment apparatus according to the present invention hasthe following advantages. First, the apparatus has improvedshock-absorbing capability to absorb vibrations of the outer tub,compared to a conventional technology.

Second, there is an effect of providing increased washing capability,compared to the conventional technology.

Third, since the upward displacement of the outer tub decreases,compared to the conventional technology, it is possible to reduce thedistance between the upper (or lower) portion of the casing and theouter tub. As a result, since the overall height of the laundrytreatment apparatus is reduced, there is an effect of enabling laundryto be easily introduced into and taken out of the apparatus.

Fourth, since the extent of shock-absorption by the shock-absorbing unitvaries depending on the amount that the outer tub is displace, shocksare gently absorbed in a normal vibration state, in which the vibrationof the outer tub is relatively low, whereas shocks are intensivelyabsorbed in an excessive vibration state, in which the vibration of theouter tub is relatively high, thereby providing an effect of assuringstability regardless of the magnitude of vibration.

DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating a washing machine according to anembodiment of the present invention;

FIG. 2 is a view illustrating a shock-absorbing unit according to anembodiment of the present invention;

FIG. 3 is a view illustrating the shock-absorbing unit;

FIG. 4 is a cross-sectional view of the shock-absorbing unit;

FIG. 5 is an exploded perspective view of the shock-absorbing unit;

FIG. 6 is a view illustrating the structure in which the shock-absorbingunit is installed on an outer tub;

FIG. 7 is a view illustrating a coupling structure between an outer tubsupport part and a movable part;

FIG. 8 is a view illustrating an irregular pitch spring;

FIG. 9 is a graph illustrating variation in elastic force withdisplacement of the outer tub, in a structure in which a pair of springsare concentrically provided in the shock-absorbing unit;

FIG. 10 is a view illustrating another embodiment of the shock-absorbingunit;

FIG. 11 is a view illustrating a shock-absorbing unit according toanother embodiment of the present invention;

FIG. 12 is a view illustrating the shock-absorbing unit shown in FIG.11;

FIG. 13 is a view illustrating the action of a first torsion spring anda second torsion spring in response to the rotation of pinions, in which(a) shows the rotational direction of the pinions, (b) shows theinstallation structure of the first torsion spring, and (b) and (c) areviewed from the left to the right in FIG. 12;

FIG. 14 is a view illustrating a shock-absorbing unit according to stillanother embodiment of the present invention;

FIG. 15 is a view illustrating a shock-absorbing unit according to afurther embodiment of the present invention;

FIG. 16 is a view illustrating a shock-absorbing unit according to afurther embodiment of the present invention;

FIG. 17 is a view illustrating the internal construction of theshock-absorbing unit shown in FIG. 16; and

FIG. 18 is a view illustrating a washing machine according to a furtherembodiment of the present invention.

BEST MODE

The advantages, features and methods for achieving those of embodimentsmay become apparent upon referring to embodiments described later indetail together with the attached drawings. However, the embodiments arenot limited to the embodiments disclosed hereinafter, but may beembodied in different modes. The embodiments are provided forcompleteness of the disclosure and to inform the scope thereof topersons skilled in this field of art. The same reference numbers mayrefer to the same elements throughout the specification.

Hereinafter, although the laundry treatment apparatus according to thepresent invention will be described with reference to a washing machine,which is one kind of laundry treatment apparatus, the present inventionshould not be construed as being limited thereto.

FIG. 1 is a view illustrating a washing machine according to anembodiment of the present invention. Referring to FIG. 1, the washingmachine 1 according to the embodiment of the present invention mayinclude a casing 10, an outer tub 2 disposed in the casing 10 so as tocontain washing water, an inner tub 3 rotatably disposed in the outertub 2 so as to contain laundry, and a drive unit 13 for rotating theinner tub 3.

The casing 10 serves to provide a space, which accommodates variouscomponents constituting the washing machine 1, such as the outer tub 2,the inner tub 3 and the drive unit 13. The casing 10 may include acabinet 11 with an upper end opening upward, and a top cover 12 coupledto the upper end of the cabinet 11 and provided at the approximatecenter thereof with an introduction port, through which clothes areintroduced into the cabinet 11.

The top cover 12 may be provided with a door 7 for opening and closingthe introduction port. Furthermore, the top cover 12 may be providedwith a control panel 17, which displays information about the state ofoperation of the washing machine 1 and provides an interface forreceiving various control commands for operation of the washing machine1.

The outer tub 2 is suspended in the casing 10. Although not shown inFIG. 1, the washing machine may be provided with a support unit forsuspending the outer tub 2 in the casing 10. The support unit may serveas a buffer capable of absorbing vibrations. The support unit will bedescribed in detail later with reference to other drawings.

The inner tub 3 may be provided on the bottom thereof with a rotatablepulsator 4. The pulsator 4 may be rotated by the drive unit 13. Thepulsator 4 may be rotated alone or in conjunction with the inner tub 3through appropriate operation of a clutch (not shown). The inner tub 3has a plurality of through holes (not shown) such that washing waterflows between the inner tub 3 and the outer tub 2.

The washing machine 1 may include a water supply conduit 5, which isconnected to an external water source such as a faucet so as to supplywater into the outer tub 2 and/or the inner tub 3, and a water supplyvalve 6 for opening and closing the water supply conduit 5. When thewater supply valve 6 is opened, the washing water, supplied through thewater supply conduit 5, is supplied into the outer tub 2 through adetergent box 32 containing detergent therein.

The washing machine 1 may include a water discharge conduit 9 throughwhich the washing water in the outer tub 2 is discharged, a waterdischarge valve 8 for opening or closing the water discharge conduit 9,and/or a water discharge pump 15 for pumping the washing water,discharged through the water discharge conduit 9, to the outside of thewashing machine 1.

FIG. 2 is a view illustrating a shock-absorbing unit according to anembodiment of the present invention. FIG. 3 is a view illustrating theshock-absorbing unit. FIG. 4 is a cross-sectional view of theshock-absorbing unit. FIG. 5 is an exploded perspective view of theshock-absorbing unit. FIG. 6 is a view illustrating the structure inwhich the shock-absorbing unit is installed on the outer tub. FIG. 7 isa view illustrating the coupling structure between an outer tub supportpart and a movable part.

Referring to FIGS. 2 to 7, the washing machine includes theshock-absorbing unit 100 for absorbing vibrations of the outer tub 2.

The shock-absorbing unit 100 includes a support rod 110, which isconnected at one end thereof to the casing 10, an outer tub support part140, which is movable along the support rod 110 and supports the outertub, at least one elastic member 161 fixedly disposed on the support rod110 so as to elastically support the outer tub support part 140 from thebottom of the outer tub support part 140, a first friction part 130disposed above the outer tub support part 140 so as to generatefrictional force between the support rod 110 and the first friction part130, and a housing 120 defining therein a space for accommodating thefirst friction part, the housing 120 being disposed at the top of theouter tub support part 140 and moving along with the outer tub supportpart 140 when the outer tub 2 vibrates, and the housing 120 beingindependently moved alone when the outer tub support part 140 is movedwithin a predetermined displacement range and being moved while pushingthe first friction part 130 when the outer tub support part 140 is movedbeyond the predetermined displacement range.

The casing 10 may include a support member 19 connected to the supportrod 110. The support rod 110 may be connected to the support member 19so as to swing or pivot within a predetermined range. The support member19 may be provided with an opening (not shown) through which the supportrod 110 passes. Accordingly, the support rod 110 may be provided at oneend thereof with an engaging protrusion (not shown), which is formed tobe larger than the opening so as to be caught from above by the supportmember 19.

The outer tub support part 140 may include a neck 141, which has alongitudinal central hole through which the support rod 110 passes andwhich has an upper end coupled to the housing 120, and a cap 142, whichis provided at the lower end of the neck 141 and is enlarged radiallyand outwardly. The cap 142 is elastically supported at the lower endthereof by the elastic member 161 and supports the outer tub 2 at theupper end thereof.

Referring to FIG. 6, the outer tub 2 may be provided with a support rodconnector 21. The support rod connector 21 may project from the sidesurface of the outer tub 2. The support rod connector 21 includes a neckreceptor 21 b through which the neck 141 vertically passes, and anopening 21 b opening laterally from the neck receptor 21 b. The width Wof the opening 21 b has to be smaller than the diameter of the neck 141such that the outer tub support part 140 cannot be laterally separated.The neck receptor 21 b has to be sized such that the cap 142 cannot passthrough the neck receptor 21 b.

The first friction part 130 may include a soft frictional member 131 forgenerating frictional force between the support rod 110 and thefrictional member 131, and a hard holder 132, which is movable along thesupport rod 110 and receives therein the frictional member 131. Thefrictional member 131 may include a plurality of frictional members 131.Correspondingly, the holder 132 may also include a plurality of holders132.

The frictional member 131 may be made of a soft material such as rubber,a porous fiber material such as felt or non-woven fabric. The frictionalmember 131 may be fitted over the support rod 110. In this case,frictional force is generated between the inner circumferential surfaceof the frictional member 131 and the outer circumferential surface ofthe support rod 110.

Since the frictional member 131, which is made of soft material, has adeformable property whereby the frictional member 131 is deformed byexternal force, there is a need to firmly hold the frictional member 131in order to maintain a constant form. In view of this, the frictionalmember 131 is preferably received in the hard holder 132.

In order to generate sufficient frictional force between the frictionalmember 131 and the support rod 110, the frictional member 131 has to bein close contact with the support rod 110. To this end, the frictionalmember 131 is preferably maintained in a somewhat compressed state bybeing compressed by the holder 132, rather than being maintained in itsoriginal form.

One of the first friction part 130 and the housing 120 may be providedwith a protrusion 123 projecting from a predetermined surface areathereof. Since there is a collision between the protrusion 123 and acounterpart while the outer tub 2 is deformed due to vibration, there isan effect of being able to reduce impact noise. Specifically, theprotrusion 123 may project from a predetermined surface of the housing120. In this case, since the contact area between the protrusion 123 andthe first friction part 130 is reduced, compared to the case where theentire surface area of the housing 120 collides with the first frictionpart 130, there is an effect of reducing noise.

The housing 120 may include an upper wall portion 121, which pushesdownward the first friction part 130 while the outer tub support part140 is displaced downward, a lower wall portion 122 disposed below theupper wall portion 121 with a predetermined distance therebetween andaccommodating therein the first friction part 130, and a plurality ofside wall portions 124 disposed between the upper wall portion 121 andthe lower wall portion 122 at predetermined intervals so as to connectthem to each other. The gap between a pair of adjacent ones of theplurality of side wall portions 124 is preferably sized so as to allowthe first friction part 130 to pass therethrough. In this case, thefirst friction part 130 may be installed in the housing 120 through thegap.

The protrusion 123 may be provided at at least one of the upper wallportion 121 and the lower wall portion 122. The protrusion 123 projectsinside the housing 120, that is, into the space S, which accommodatesthe first friction part 130.

The first friction part 130 may include a pair of frictional members 131longitudinally arranged along the support rod 110, and a pair of holders132 respectively receiving the pair of frictional members 131. Each ofthe pair of holders 132 may include a pipe portion 132 a in which thefrictional member 131 is fitted, and a flange portion 132 b extendinglaterally from one end of the pipe portion 132 a. The pair of holders132 are coupled to each other at the other ends opposite the one endshaving the flange portions 132 b. Accordingly, the upper and lower endsof the holder assembly constituted by the pair of holders 132 arerespectively provided with the flange portions 132 b. The pair ofholders 132 are preferably coupled to each other in a detachable manner.One of the pair of holders 132 may be provided with a hook, and theother of the pair of holders 132 may be provided with a loop, whichengages with the hook. For compatibility, the pair of holders 132 may beconfigured so as to have the same structure. In this case, the hooks andthe loops may be alternately arranged along the circumference of thepipe portion 132 a of each of the holders 132.

The first friction part 130 may include an outer cylindrical pipe 133,which is fitted over the holder 132 and secured between the pair offlange portions 132 b. The outer pipe 133 may be made of a magneticmaterial, for example, metal.

One of the housing 120 and the outer tub support part 140 may beprovided with a coupling protrusion 145, and the other of the housing120 and the outer tub support part 140 may be provided with a couplingloop 125 having a hole 125 h with which the coupling protrusion 145engages. The coupling protrusion 145 may include a plurality of couplingprotrusions. In this case, the coupling loops 125 may also include aplurality of coupling loops corresponding in number to the number ofcoupling protrusions 145. The engagement between the coupling protrusion145 and the coupling loop 125 may be achieved by relative rotationbetween the housing 120 and the outer tub support part 140 about thesupport rod 110. In coupling between the housing 120 and the outer tubsupport part 140, regardless of the locations between the coupling loops125 at which the coupling protrusions 145 are positioned, the couplingprotrusions 145 may be engaged with the coupling loops 125 by a simplemanipulation of rotating the housing 120 or the outer tub support part140, thereby providing an advantage of making assembly easy. Thecoupling protrusion may be provided with an inclined surface 145 a suchthat the coupling loop 125 can smoothly be fitted over the couplingprotrusion when the housing 120 or the outer tub support part 140 isrotated.

The inner tub 3 may be rotated in an unbalanced state while the outertub 3 is rotated about a fixed axis. Hence, a force capable of causingtorsion or twisting of the neck 141 may be applied to the neck 141.Accordingly, because an intensive frictional force is applied betweenthe first friction part 130 and the support 110, the force of causingtwisting may lower the rigidity of the neck 141. Therefore, the lengthof the neck 141 has to be set to be equal to or greater than a length atwhich twisting is sufficiently resisted.

The shock-absorbing unit 100 may further include a second friction part170, which is fixedly disposed relative to the cap 142 so as to createfrictional force between the support rod 110 and the second frictionpart 170 upon vibration of the outer tub 2. The second friction part 170may include a cylindrical housing 171 and a frictional member 172disposed in the housing 171 so as to create frictional force between thesupport rod 110 and the frictional member 172.

The cap 142 may include an upper wall portion 142 a for supporting theouter tub 2, a lower wall portion 142 b spaced apart from the upper wallportion 142 a and elastically supported by the elastic member 161, and aplurality of side wall portions 142 c, which are disposed between theupper wall portion 142 a and the lower wall portion 142 b and arecircumferentially spaced apart from each other at intervals so as toconnect the upper wall portion 142 a to the lower wall portion 142 b.The spacing between a pair of adjacent ones of the plurality of sidewall portions 142 c is preferably sized so as to allow the secondfriction part 170 to pass therethrough.

The shock-absorbing unit 100 may include a first spring 161 and a secondspring 162, which are concentrically arranged. The second spring 162begins to be compressed after the first spring 161 has been compressedto a predetermined extent by being pushed by the outer tub support part140. Accordingly, when displacement of the outer tub 2 due to vibrationis within a predetermined range, the shock-absorbing function isfulfilled only by the first spring 161. Meanwhile, when displacement ofthe outer tub 2 exceeds the predetermined range, the shock-absorbingfunction is fulfilled by both the first spring 161 and the second spring162. Consequently, the shock-absorbing function can be efficientlyfulfilled even when excessive vibration of the outer tub 2 is generateddue to resonance, thereby assuring the endurance and stability of thewashing machine.

The shock-absorbing unit 100 may further include a movable member 150,which is movable along the support rod 110 and is elastically supportedby the second spring 162. The movable member 150 is moved by the outertub support part 140 after the first spring 161 has been compressed to apredetermined extent.

The second spring 162 may be disposed inside the first spring 161. Thefirst spring 161 and the second spring 162 may be supported by a commonbase 112. In this case, the second spring 162 has a shorter length thanthe first spring 161. Hence, after the first spring 161 is compressed bythe length difference between the first spring 161 and the second spring162, the second spring 162 begins to be compressed along with the firstspring 161.

The support rod 110 may be provided at the lower end thereof with thebase 112 by which the first spring 161 and/or the second spring 162 issupported. The base 112 may be provided with an annular partition wall112 a projecting from the surface thereof that is in contact with thefirst spring 161. The first spring 161 may be disposed such that thepartition wall 112 a is positioned inside the first spring 161, and thesecond spring 162 may be disposed inside the partition wall 112 a. Inorder for the second spring 162 to be firmly held without shaking, thepartition wall 112 a may preferably have an inner diameter that issubstantially equal to the outer diameter of the second spring 162.

After completion of assembly, at least one of the first spring 161 andthe second spring 162 is preferably coupled to the base 112 so as toprevent rotation of the at least one spring about the support rod 110.The base 112 may be provided with a holder (not shown) for holding theend of the spring 161. The end of the spring may be engaged with theholder in a rotating manner. In this case, the spring 161 is graduallyengaged with the holder from the end thereof as the spring 161 isrotated in one rotational direction. When the spring 161 cannot berotated any further, the engagement between the spring and the holdermay be completed.

The first spring 161 and the second spring 162 are preferably arrangedin a concentric manner such that the elastic force of the first spring161 or the second spring 162 is precisely exerted in the longitudinaldirection of the support rod 110. In this case, the first spring 161 andthe second spring 162 define concentric circles when viewed inhorizontal section.

The elastic member constituting the shock-absorbing unit may have amodulus of elasticity that varies in a non-linear fashion according to aload. An example of the elastic member is an irregular pitch spring 860(see FIG. 8), which has sections having different pitches.

In the case where two springs 161 and 162 are provided as describedabove, the elastic force (or restoring force, Y-axis) with displacement(X-axis) of the outer tub 2 (or the outer tub support part 140)increases at a constant inclination k1 within a section in which theshock-absorbing function is fulfilled only by one spring 161, and thenlinearly increases in a different inclination k2 from the point Pc atwhich the shock-absorbing function is fulfilled by both the springs 161and 162, as illustrated in FIG. 9.

Meanwhile, in the case where the irregular pitch spring 860 is applied(see FIG. 8), the increase in elastic force (Y-axis) with displacementof the outer tub 2 continuously changes in inclination in a nonlinearmanner. Consequently, the shock-absorbing function may be more smoothlyfulfilled throughout the entire range in which the outer tub 2 isdisplaced. The irregular pitch spring 860 may include a first section861 extending at a certain pitch P1 and a second section 862 having apitch P2 different from the first section 861. In some embodiments, theirregular pitch spring 860 may include more sections, adjacent sectionshaving different pitches. In this embodiment, a third section 863 isfurther provided under the second section 862. Although the thirdsection 863 may have the same pitch as the first section 861, there isno need for it to be limited thereto. Among the first section 861, thesecond section 862 and the third section 863, the first sectionpreferably has the greatest pitch P2.

FIG. 10 is a view illustrating another embodiment of the shock-absorbingunit. Referring to FIG. 10, this embodiment may include at least onemagnet 190, which causes attractive force attributable to a magneticfield between the first friction part 130 and the housing 120 in adirection perpendicular to the direction in which the first frictionpart 130 is displaced. In this embodiment, the magnet 190 may bedisposed on the housing 120, and the first friction part 130 may beprovided with metal capable of creating attractive force due to therelationship between the magnet 190 and the metal. The pipe 133 may bepreferably made of the metal. Examples of the metal may include ironsuch as steel use stainless (SUS), nickel, cobalt and the like.

The first friction part 130 may be reliably moved along the support rod110 without lateral shaking by means of the attractive force actingbetween the magnet 190 and the first friction part 130.

Specifically, it is preferable that the magnetic force from the magnet190 act symmetrically with respect to the longitudinal axis of thesupport rod 110. To this end, the magnet 190 may be preferablyconfigured to have the shape of a band or annulus surrounding the sidewall portion 124 of the housing 120, or may be preferably constituted bya plurality of magnets, which are symmetrically arranged.

It is preferable that the first friction part 130 be spaced apart fromthe magnet 190 with a predetermined distance therebetween so as to causeindirect action of magnetic force, rather than being in contact with themagnet 190 so as to cause direct action of magnetic force. The magnet190 may be disposed on the outer circumferential surface of the sidewall portion 124 of the housing 120. In FIG. 10, the side wall portionincludes a side wall portion 124(1) and a side wall portion 124(2),which are arranged to be symmetrical with each other.

FIG. 11 is a view illustrating a shock-absorbing unit 200 according toanother embodiment of the present invention. FIG. 12 is a viewillustrating the shock-absorbing unit 200 shown in FIG. 11. FIG. 13 is aview illustrating the action of a first torsion spring 250 a and asecond torsion spring 250 b by rotation of pinions 224 a and 224 b, inwhich (a) shows the rotational direction of the pinions 224 a and 224 b,(b) shows the installation structure of the first torsion spring 250 a,and (c) shows an installation structure of the second torsion spring 250b. In this figure, (b) and (c) are viewed from the left to the right inFIG. 12.

Referring FIGS. 11 to 13, the washing machine according to theembodiment of the present invention may include a shock-absorbing unit200 for absorbing vibrations of the outer tub 2.

The shock-absorbing unit 200 may include a rack 214 extendingvertically, one or more pinions 224 and 224 b, which are rotated bycooperation with the rack 214, and one or more torsion elements 250 aand 250 b, which are torsionally deformed so as to dampen the rotationalmovement of the pinions 224 a and 224 b when the pinions 224 a and 224 bare rotated. Although a pair of pinions 224 a and 224 b are shown in theattached drawing, only one of the pair of pinions 224 a and 224 b mayalternatively be provided, without being limited thereto.

More specifically, the shock-absorbing unit 200 may include an outer tubsupport part 210 for supporting the outer tub 2 in a suspended state inthe casing 10, and a torsional damper 220 for generating torsionalmoment as the outer tub 2 vibrates. One of the outer tub support part210 and the torsional damper 220 may be provided with the rack 214, andthe other of the outer tub support part 210 and the torsional damper 220may be provided with the pinions 224 a and 224 b. Hereinafter, anexample in which the outer tub support part 110 is provided with therack 214 and the torsional damper 220 is provided with the pinions 224 aand 224 b will be described.

One end of the outer tub support part 210 may be supported by the casing10, and the other end of the outer tub support part 210 may include asupport rod 211 connected to the lower portion of the outer tub 2. Thecasing 10 may include a support member 240 for supporting one end of thesupport rod 211. The support member 240 may be integrally formed withthe cabinet 11 or the top cover 12, or may be formed as a separatecomponent and coupled to the cabinet 11 or the top cover 12.

The support member 240 may have an opening through which the support rod211 passes. Therefore, one end of the support rod 211 may project upwardthrough the opening. The support rod 211 may be provided at one endthereof with a support protrusion 212. The support rod 211 may beprovided at the other end thereof with an outer tub connector 213connected to the outer tub 2. The outer tub 2 may be provided with thesupport rod connector 21, which engages with the outer tub connector213. The support rod connector 21 may be provided at the lower portionof the outer tub 2 so as to project from the outer surface of the outertub 2. The support rod connector 21 is partially opened at a sidesurface thereof so as to allow the support rod 211 to be insertedtherethrough. The support rod 211, which is inserted through the openedportion, engages at the lower end thereof with the bottom surface of thesupport rod connector 21.

At least one spring 260, which is inserted over the support rod 211 andis disposed between the support member 240 and the support protrusion212, may be further provided. The spring 260 is supported at the lowerend thereof by the support member 240, and elastically supports thesupport protrusion 212 at the upper end thereof.

The support rod 211 may be provided with the rack 214. The rack 214 maybe integrally formed with the support rod 211, or may be formed as aseparate component and coupled to the support rod 211. The rack 214 ispreferably disposed within a range such that the rack 214 is always inengagement with the pinions 224 a and 224 b when the outer tub 2vibrates.

The torsional damper 220 may include containers 225 a and 225 b, whichaccommodate the torsion elements 250 a and 250 b therein, and thepinions 224 a and 224 b, which are rotated about a rotating shaftpassing through the containers 225 a and 225 b.

A holding part 230 for holding the position of the torsional damper 220relative to the support member 240 may be provided. The holding part 230may include a cylinder 235, which has an elongate hole, through whichthe support rod 111 passes, and which is provided at the upper endthereof with an engaging portion 236 coupled thereto, and a holdingframe 231, which is connected to the lower end of the cylinder 235 so asto hold the torsional damper 220.

The holding frame 231 is coupled to the lower end of the cylinder 235,and has one or more openings h1 and h2 through which the support rod 211passes. In this embodiment, the upper opening h1, through which thesupport rod 211 passes, is formed in an upper frame 231 a connected tothe lower end of the cylinder 235, side frames 231 b and 231 c extenddownward from opposite lateral sides of the upper frame 231 b, and thelower opening h2, through which the support rod 211 passes, is formed ina lower frame 231 d connecting the pair of side frames 231 b and 231 bto each other. The torsional damper 220 may be disposed in the spacedefined by the frames, and may be fixedly coupled to the side frames 231b and 231 c.

Since the torsional damper 220 is disposed in the inner regionsurrounded by the holding frame 231, it is possible to prevent thetorsional damper 220 from colliding with the outer tub 2 or the casing10.

The torsion elements 250 a and 250 b is made of a deformable elasticmember so as to be twist-deformed by rotation of the pinions 224 a and224 b. In particular, the torsion elements are elastically deformed,thereby creating a torsional resisting moment. The torsion elements 250a and 250 b may include helical torsion springs, elastic torsion bars,which are deformed in section by external force, or the like.Hereinafter, an example in which the torsion elements 250 a and 250 bare embodied as torsion springs will be described.

The rotational direction of the pinions 224 a and 224 b when the outertub 2 is moved downward during vibration thereof is opposite to therotational direction of the pinions 224 a and 224 b when the outer tub 2is moved upward during vibration thereof. Accordingly, the torsionsprings 250 a and 250 b may be twisted upon increase in downwarddisplacement of the outer tub 2 and may be untwisted upon increase inupward displacement of the outer tub 2, depending on the manner in whichthe torsion springs are installed. In contrast, the torsion springs 250a and 250 b may be twisted upon increase in upward displacement of theouter tub 2 and may be untwisted upon increase in downward displacementof the outer tub 2, depending on the manner in which the torsion springsare installed.

Since the outer tub 2 is always subjected to force in the direction ofgravitational force attributable to the load of laundry or water as wellas its intrinsic weight, it is important to address drooping of theouter tub 2. Therefore, at least one of the torsion springs 250 a and250 b is preferably installed so as to be twisted when the outer tub 2is displaced downward.

The torsion springs 250 a and 250 b may include a plurality of torsionsprings. In this case, there may be provided the first torsion spring250 a and the second torsion spring 250 b, which create a torsionalresisting moments in different directions when the pinions 224 a and 224b are rotated in one direction. For example, when the outer tub 2 isdisplaced downward, the first torsion spring 250 a is twisted, therebyserving as a resistor for dampening the downward displacement. Incontrast, when the outer tub 2 is displaced upward, the second torsionspring 250 b is twisted, thereby serving as a resistor for dampeningupward displacement.

More specifically, referring to FIGS. 12 and 13, the first torsionspring 250 a is accommodated in the first container 225 a, and thesecond torsion spring 250 b is accommodated in the second container 225b. One end E1 of each of the torsion springs 250 a and 250 b may becoupled to the rotating shaft of the pinion 224 a or 224 b, and theother end E2 of each of the torsion springs 250 a and 250 b may becoupled to the container 225 a or 225 b. In this arrangement, when thepinions 224 a and 224 b are rotated in a positive (+) direction whilemoving downward along the rack 214, the second torsion spring 250 b istwisted, thereby creating a torsional resisting moment in a negative (−)direction. In contrast, when the pinions 224 a and 224 b are moved alongthe rack 214, the pinions 224 a and 224 b are rotated in a negative (−)direction, and the first torsion spring 224 a is twisted, therebycreating a torsional resisting moment in a positive (+) direction.Accordingly, when the outer tub 2 vibrates, a predetermined level orhigher of shock-absorbing force may always be applied, regardless of thedirection in which the outer tub 2 is displaced.

Although the first torsion spring 250 a and the second torsion spring250 b may be operated via the rotation of a single common pinion, thefirst pinion 224 a, associated with the first torsion spring 250 a, andthe second pinion 224 b, associated with the second torsion spring 250b, may be provided, as in this embodiment. In this case, the firstpinion 224 a and the second pinion 224 b may include a common rotatingshaft.

FIG. 14 is a view illustrating a shock-absorbing unit 200′ according toa still another embodiment of the present invention. Hereinafter, thesame components as those of the previous embodiments will be denoted bythe same reference numerals, and descriptions thereof are omitted byadopting those of the previous embodiments.

Referring FIG. 14, the shock-absorbing unit 200′ may include a firstspring 260, and a second spring 270, which is concentrically arrangedwith respect to the first spring 260 and which begins to be deformedwhen the first spring 260 is deformed to a predetermined level orhigher. The first spring 260 and the second spring 270 may havedifferent moduli of elasticity.

When the displacement of the outer tub 2 attributable to vibration islower than a predetermined value, the shock-absorbing function isfulfilled only by the first spring 260, which is compressed by thesupport protrusion 212. When the displacement of the outer tub 2 exceedsthe predetermined value, the shock-absorbing function is fulfilled byboth the first spring 260 and the second spring 270. A movable member280 may be provided so as to be moved along the support rod 211 betweenthe support member 240 and the support protrusion 212. The movablemember 280 is elastically supported by the second spring 270. When thedisplacement of the outer tub 2 exceeds the predetermined value, themovable member 280 is moved by the support protrusion 212, therebycompressing the second spring 270. When the pressure applied to themovable member 280 by the support protrusion 212 is released by reversalof the direction of movement of the outer tub 2, the movable member 280is returned to its normal position by the restoring force of the secondspring 270.

The second spring 270 may have a smaller diameter than the first spring260. In this case, the second spring 270 is disposed inside the secondspring 270. The second spring 270 may also be configured to be shorterthan the first spring 260.

When the displacement of the outer tub 2 attributable to vibrationthereof is within a relatively small range, the shock-absorbing functionis fulfilled only by the first spring 260, among the first spring 260and the second spring 270. Accordingly, appropriate shock-absorbingforce is applied during the generation of smaller vibrations. Incontrast, when the displacement of the outer tub 2 increases beyond thesmall range, the shock-absorbing function is fulfilled by both the firstspring 260 and the second spring 270, thereby enhancing stability in theevent of excessive vibration.

Since the laundry treatment apparatuses according to the embodiments,which have been described with reference to FIGS. 11 to 14, areconfigured to fulfill a shock-absorbing function by means of the torsionelements, which are twisted by displacement of the outer tub, there isan effect of easily changing the direction of the torsional resistingmoment, depending on the arrangement of the torsion elements.

FIG. 15 is a view illustrating a shock-absorbing unit according to afurther embodiment of the present invention. Referring to FIG. 15, awashing machine according to the further embodiment of the presentinvention may include the shock-absorbing unit 300 for absorbingvibration of the outer tub 2.

The shock-absorbing unit 300 may include a support rod 310, a firstfluid container 340 and a second fluid container 350.

The support rod 310 is suspended in the casing, and is connected to theouter tub 2. When the outer tub 2 is displaced upward or downward due tovibrations, the support rod 310 is correspondingly displaced in the samedirection as the outer tub 2.

The first fluid container 340 contains fluid therein, and the amount offluid contained in the first fluid container 340, that is, the housingcapacity C, is changed due to the vibration of the outer tub 20. Thehousing capacity may decrease when the outer tub 2 is displaced downward(ΔC<0), and may increase when the outer tub 2 is displaced upward(ΔC>0). The variation in housing capacity of the first fluid container340 (ΔC), that is, the capacity variation is discharged from orintroduced into the first container 340.

An amount of fluid equal to the variation amount (ΔC) is circulatedbetween the second fluid container 350 and the first fluid container340. Specifically, when the housing capacity of the first fluidcontainer 340 decreases, an amount of fluid equal to the decreasedvariation amount is transferred from the first fluid container 340 tothe second fluid container 350 (see the direction of the arrow in FIG.15). In contrast, when the housing capacity of the first fluid container340 increases, an amount of fluid equal to the increased variationamount is transferred from the second fluid container 350 to the firstfluid container 340.

The support rod 310 is provided at the end thereof with a dynamicpressure actuator 312, which is movably disposed in the second fluidcontainer 350 so as to exert the dynamic pressure of the fluid in thesecond fluid container 350 in the direction opposite the direction inwhich the outer tub 2 moves. The dynamic pressure is caused bycirculation of fluid between the first fluid container 340 and thesecond fluid container 350. Positive pressure is applied to the dynamicpressure actuator 312 when fluid is transferred from the first fluidcontainer 340 to the second fluid container 350, and negative pressureis applied to the dynamic pressure actuator 312 when the fluid istransferred from the second fluid container 350 to the first fluidcontainer 340. Specifically, when the outer tub 2 is displaced downwarddue to the vibration thereof, positive pressure is applied to thedynamic pressure actuator 312 from the fluid in an upward direction,that is, in the direction in which the fluid supports the dynamicpressure actuator 312 (see the direction of the arrow in FIG. 15). As aresult, the downward movement of the support rod 310 is attenuated dueto the positive pressure, and the downward movement of the outer tub 2is correspondingly attenuated. In contrast, when the outer tub 2 isdisplaced upward, negative pressure is applied to the dynamic pressureactuator 312 from the fluid. As a result, the upward movement of thesupport rod 310 is attenuated, and the upward movement of the outer tub2 is correspondingly attenuated.

In this way, the housing capacity of the first fluid container 340varies due to the vibration of the outer tub 2, and the variation in thehousing capacity of the first fluid container 340 causes the transfer ofan amount of fluid corresponding to the variation amount. Since thedynamic pressure caused by the variation in the housing capacity servesin turn to attenuate the displacement of the support rod 310, thevibration of the outer tub 2, which is connected to the support rod 310,is also attenuated, thereby improving the stability of the entiresystem.

The shock-absorbing unit 300 may include a fluid channel, which enablesfluid to be circulated between the first fluid container 340 and thesecond fluid container 350. The fluid channel, which is intended toestablish communication between the first fluid container 340 and thesecond fluid container 350, may be embodied in various fashions.Hereinafter, although an example in which the fluid channel is formed inthe support rod 310 will be described, the fluid channel may be formedseparately from the support rod 310, without being limited thereto.

The support rod 310 may include a pipe portion defining a longitudinalcentral hole 311 a, and the circulation of fluid between the first fluidcontainer 340 and the second fluid container 350 may be achieved throughthe central hole 311 a. The support rod 310 may be at least partiallydisposed in the first fluid container 340, and the pipe portion 311 maybe provided with a flow opening 311 b, which allows the space in thefirst fluid container 340 to communicate with the central hole 311 a.

The first fluid container 340 may include a cylinder 320 having an openupper end, and a piston 330, which defines, in conjunction with thecylinder 320, a space S for containing fluid therein and which ismovable with respect to the cylinder 320. The piston 330 is integrallyformed with the outer tub 2, and the volume of the space S correspondingto the housing capacity of the first fluid container 340 varies as thepiston 330 moves.

The casing 10 may include a support member 19 for supporting the secondfluid container 340. The support member 19 may be integrally formed withthe casing 10, or may be formed separately from the casing 10 and may becoupled to a constituent component thereof. The support member 19 may beprovided with a through hole 19 h, through which the pipe portion 311passes. The pipe portion 311 may be disposed at the lower end thereofinside of the first fluid container 340 below the support member 19, andmay be disposed at the upper end thereof inside the second fluidcontainer 350 on the support member 19. The pipe portion 311 may passthrough the piston 330, and may be connected to the cylinder 320 in thespace S. The piston 330 may be provided with a through hole 330 hthrough which the pipe portion 111 passes.

The pipe portion 311 may be provided at the upper end thereof with thedynamic pressure actuator 312. The dynamic pressure actuator 312 may beintegrally formed with the pipe portion 311, or may be separately formedand may be coupled to the pipe portion 311. The dynamic pressureactuator 312 may be constituted by a plate body, which is enlargedradially and outwardly from the upper end of the pipe portion 311.

The outer tub 2 may be provided with a piston connector 22. The pistonconnector 22 may include a connecting protrusion 22 a, which projectsoutward from the outer tub 2 and is supported by the piston 330. Theconnecting protrusion 22 a may be provided with a through hole 22 h at aposition corresponding to the through hole 330 h so as to allow thesupport rod 310 to pass therethrough. The piston protrusion 22 mayfurther include a partition wall 22 b, which extends downward from theouter end of the connecting protrusion 22 a. The piston 330 may befirmly supported by the partition wall 22 b even when the support rod310 is pivoted with respect to the through hole 22 h.

The shock-absorbing unit 300 may further include an elastic member 360,which is fixedly disposed on the cylinder 320 so as to elasticallysupport the piston 330. The elastic member 360 may be embodied as aspring. The piston 330 may include a piston body 331, which is movablein the cylinder 320, and a plate 332, which extends laterally from theupper end of the piston body 331.

A support protrusion 322 may extend outward from the lower end of thecylinder 320 to support one end of the elastic member 360. In this case,the cylinder 320 is disposed inside the elastic member 360, and theupper end of the elastic member 360 supports the plate 332 of the piston330.

However, the elastic member 360 may be disposed inside the cylinder 320,without being limited thereto. In this case, there is no need to providethe plate 332, and the elastic member 360 is supported by the bottom ofthe cylinder 320 so as to elastically support the piston 330. When theouter tub 2 is displaced downward, the piston 330 presses the elasticmember 360, thereby compressing the elastic member 360. In contrast,when the outer tub 2 is displaced upward, the elastic member 360 isrestored to its normal position by its own elastic force.

The shock-absorbing unit 300 may further include a flow guide 370disposed inside the second fluid container 350. When the housingcapacity of the first fluid container 340 is reduced, the flow guide 370serves to guide fluid, which is introduced into the second fluidcontainer 350 through the pipe portion 111, in the downward direction ofthe dynamic pressure actuator 312.

The flow guide 370 may be disposed above the dynamic pressure actuator312. The flow guide 370 may include a partition plate 371 for dividingthe second fluid container 350 into upper and lower parts, and a sidewall 372, which projects from the circumferential edge of the partitionplate 371 and is movable along the inner circumference surface of thesecond fluid container 350.

The fluid, which is introduced into the second fluid container 350 fromthe first fluid container 340 through the pipe portion 311, flows in alateral direction between the dynamic pressure actuator 312 and the flowguide 370. Specifically, the fluid is discharged toward the lowersurface 371 a of the flow guide 370 from the pipe portion 311. Aftercolliding with the lower surface 371 a of the flow guide 370, the fluidflows in a lateral direction between the lower surface 371 a of the flowguide 370 and the upper surface 312 a of the dynamic pressure actuator312.

The fluid, which has flowed in the lateral direction, is turned downwardin flow direction, thereby applying pressure to the lower surface of thedynamic pressure actuator 312, particularly to the lower surface 371 aof the partition plate 371. To this end, a distance d may be definedbetween the dynamic pressure actuator 312 and the second fluid container350 (or between the dynamic actuator 312 and the flow guide 370). Thefluid, which has flowed in the lateral direction between the flow guide370 and the dynamic pressure actuator 312, is turned downward and flowsthrough the distance d. As a result, dynamic pressure is finally appliedto the lower surface 312 b of the dynamic pressure actuator 312. Theflow guide 370 may be moved by the hydraulic pressure in the secondfluid container 350.

The shock-absorbing unit 300 may further include a seal 382 for sealingthe gap between the flow guide 370 and the second fluid container 350.Although the seal 382 is preferably constituted by a soft O-ring, thepresent invention is not limited thereto. The seal 382 may be secured tothe outer circumferential surface of the flow guide 370 (e.g. the outercircumferential surface of the side wall 372) or the innercircumferential surface of the second fluid container 350.

The shock-absorbing unit 300 may further include a seal 381, which sealsthe clearance between the piston 330 and the cylinder 320 to prevent theleakage of fluid from the first fluid container 340. Although the seal381 is preferably constituted by a soft O-ring, the present invention isnot limited thereto. The seal 381 may be secured to the outercircumferential surface of the piston 330 or the inner circumferentialsurface of the cylinder 320.

Although the first fluid container 340 is disposed under the outer tub 2in this embodiment, it may also be disposed above the outer tub 2 insome embodiments, without being limited thereto.

FIG. 16 is a view illustrating a shock-absorbing unit according to afurther embodiment of the present invention. FIG. 17 is a viewillustrating the internal construction of the shock-absorbing unit shownin FIG. 16. Referring to FIGS. 16 and 17, the washing machine mayinclude the shock-absorbing unit 400 according to the further embodimentof the present invention. The shock-absorbing unit 400 may include asupport rod 410, a first fluid container 440 and a second fluidcontainer 450.

The support rod 410 serves to suspend the outer tub 2 in the casing 10,and is connected to the outer tub 20. When the outer tub 2 is displaceupward or downward due to the vibration thereof, the support rod 410 isalso displaced in the same direction as the outer tub 2.

The first fluid container 440 contains fluid therein, and the amount offluid contained in the first fluid container 440, that is, the housingcapacity C varies as the outer tub 2 vibrates. The housing capacity maydecrease when the outer tub 2 is displaced downward (ΔC<0), and mayincrease when the outer tub 2 is displaced upward (ΔC>0). An amount offluid equal to the variation amount (ΔC) in the housing capacity of thefirst fluid container 440 is discharged from the first fluid container440 or is introduced into the first fluid container 440.

An amount of fluid corresponding to the variation amount (ΔC) iscirculated between the second fluid container 450 and the first fluidcontainer 440. Specifically, when the housing capacity of the firstfluid container 440 decreases, an amount of fluid equal to the decreasedvariation amount is transferred from the first fluid container 440 tothe second fluid container 450. In contrast, when the housing capacityof the first fluid container 440 increases, an amount of fluid equal tothe increased variation amount is transferred from the second fluidcontainer 450 to the first fluid container 440.

The support rod 410 may be disposed so as to pass through the firstfluid container 440 and the second fluid container 450. The end of thesupport rod 410 that extends downward through the first fluid container440 may be connected to the outer tub 2, and the other end of thesupport rod 410 may be disposed inside the second fluid container 450.The shock-absorbing unit 400 may further include a fluid flow conduit490, which allows fluid to be circulated between the first fluidcontainer 440 and the second fluid container 450. A dynamic pressureactuator 470 may be provided at the other end of the support rod 410.

The outer tub 2 may be provided with the support rod connector 21 towhich the lower end of the support rod 410 is connected. The support rodconnector 21 may be provided at the lower portion of the outer tub 2 soas to project from the outer surface of the outer tub 2. The support rodconnector 21 is partially opened in a side surface thereof so as toallow the support rod 410 to be inserted therethrough. The support rod410, which is inserted through the opened portion, engages at the lowerend thereof with the bottom surface of the support rod connector 21.

Unlike the above-described embodiments, the fluid flow conduit 490 maybe a component independent of the support rod 410, and may be preferablyconstituted by a plurality of tubes, which allow the upper portion ofthe first fluid container 440 to communicate with the lower portion ofthe second fluid container 450.

The dynamic pressure actuator 270 may include a caulking 470, which isin close contact with the inner circumferential surface of the secondfluid container 450. The caulking 470 is moved upward and downward inthe second fluid container 450 by displacement of the outer tub 2.

The shock-absorbing unit 400 may further include an elastic member 460,which is disposed inside the second fluid container 450 so as toelastically support the caulking 470. The elastic member 460 may beembodied as a spring. When the outer tub 2 is displaced downward, thecaulking 470 is lowered along with the support rod 410. At this time,since both the supporting force exerted by the elastic member 460 andthe dynamic pressure of the fluid introduced into the second fluidcontainer 450 due to the decrease in the housing capacity of the firstfluid container 440, are applied to the caulking 470, the downwarddisplacement of the outer tub 2 is attenuated.

In contrast, when the outer tub 2 is displaced upward, the housingcapacity of the first fluid container 440 increases. As a result,negative pressure is created in the second fluid container 450, andfluid is transferred from the second fluid container 450 to the firstfluid container 440 through the fluid flow conduit 490.

The first fluid container 440 may include a bellows tube 441, which issupported by the casing 10. Since the bellows tube 441 is expanded orcontracted due to vibration of the outer tub 2, the capacity to holdfluid, that is, the internal volume of the bellows tube, varies. Thebellows tube 441 includes a plurality of wrinkles so as to becollapsible due to variation in the longitudinal external force appliedthereto, and is preferably made of a soft material.

The casing 10 may include a support member 19 having an opening throughwhich the support rod 410 passes, and the first fluid container 440 maybe supported by the support member 19. The support member 19 may beintegrally formed with the casing 10, or may be separately formed andmay be coupled to a component constituting the casing 10. The supportmember 19 may be provided with a through hole through which the supportrod 410 passes.

The shock-absorbing unit 400 may further include a slide member 485,which is movable along the support rod 410. The slide member 485 may bedisposed under the first fluid container 440. Since the slide member 485is supported by the support member 19 when the outer tub 2 is displaceddownward, the slide member 485 is maintained in a state of being inclose contact with the first fluid container 440. When the outer tub 2is displaced upward, the housing capacity of the first fluid container440 increases (i.e. the bellows tube 441 is expanded), and the slidemember 485 is correspondingly lowered. At this time, the slide member485 is also maintained in the state of being in close contact with thefirst fluid container 440. Consequently, the slide member 485 may bealways in close contact with the first fluid container 440, therebyproviding a reliable airtight seal for the first fluid container 440.

In this embodiment, although the support member 19 is disposed at anupper position inside the casing 10, the present invention is notlimited thereto. In some embodiments, the support member 19 may bedisposed at a lower position inside the casing 10. In this case, theoverall structure of the shock-absorbing unit 400 is changed such thatthe first fluid container 440 is disposed in accordance with theposition of the support member 19.

FIG. 18 is a view illustrating a washing machine according to a furtherembodiment of the present invention. Referring to FIG. 18, in thewashing machine according to this embodiment, an outer tub 2′ includesan upper outer tub part 25 fixed to the casing 10, a lower outer tubpart 26, which is disposed under the upper outer tub part 25 and isbuffered by the shock-absorbing unit 100, 200, 200′, 300 or 400, and aconnecting part 27, which connects the upper outer tub part 25 to thelower outer tub part 26 and which is deformed by the displacement of thelower outer tub part 26. For smooth deformation, the connecting part 27is preferably made of a soft material having resiliency, such as rubberor synthetic resin.

The connecting part 27 may include an upper coupler 27 a, which isconfigured to have an annular section corresponding to the horizontalsection of the outer tub 2′ and which is coupled to a lower end 25 a ofthe upper outer tub part 25, a lower coupler 27 b, which is coupled toan upper end 26 a of the lower outer tub part 26, and a foldable part27, which is disposed between the upper coupler 27 a and the lowercoupler 27 b and which is folded at least once. Accordingly, there is anadvantage in that shocks are absorbed by the folding of the foldablepart 27 in response to vibrations of the lower outer tub part 26.

The coupling between the upper coupler 27 a and the upper outer tub part25 and the coupling between the lower coupler 27 b and the lower outertub part 26 are preferably implemented in a sealable manner. To thisend, the upper coupler 27 a may be coupled in such a manner as tosurround the lower end 25 a of the upper outer tub part 25. The lowerend 25 a of the upper outer tub part 25 or the upper end 26 a of thelower outer tub part 26 may be bent in various fashions. In this case,the upper coupler 27 a or the lower coupler 27 b is preferablyconfigured so as to have a structure corresponding to the bent structurefor the sake of robustness and airtightness of the coupling.

The washing machine may further include an outer tub-fixing member 30for fixing the upper outer tub part 25 to the casing 10. The outertub-fixing member 30 may be fixedly disposed in the casing 10, and maybe configured to surround at least a portion of the outer circumferenceof the upper outer tub part 25. The outer tub-fixing member 30 mayinclude a plurality of outer tub-fixing members, which are providedalong the outer circumference of the upper outer tub part 25.

The lower outer tub part 26 may be provided with the shock-absorbingunit 100, 200, 200′, 300 or 400) according to the above-describedembodiments. The lower outer tub part 26 may be provided with a supportrod connector 21 (see FIG. 11) or the piston connector 22 (see FIG. 15),depending on the kind of shock-absorbing unit 100, 200, 200′, 300 or400. In FIG. 18, circle A and circle B indicate positions at which theshock-absorbing unit 100, 200, 200′, 300 or 400 can be installed. CircleA indicates a lower portion of the lower outer tub part 26, and circle Bindicates an upper portion of the lower outer tub part 26. Specifically,the piston connector 22 (or the support rod connector 21) may be formedat a predetermined position on the lower outer tub part 26. Inparticular, the piston connector 22 may be formed not only at the lowerportion A of the lower outer tub part 26 but also at the upper portion Bof the lower outer tub part 26. The structure of the shock-absorbingunit 100, 200, 200′, 300, 400 may also be changed within the scope andspirit of the present invention, in accordance with the position of thepiston connector 22 (or support rod connector 21).

The vibration of the lower outer tub part 26 can be attenuated by meansof the shock-absorbing unit 100 or 200, unlike the conventionaltechnology. Furthermore, since the upper outer tub part 25 is alwaysfixed to the casing 10 even when vibrates are generated, it is possibleto fundamentally prevent collisions with the upper portion of the casing(for example, the top cover 12). Consequently, the distance between theupper outer tub part 25 and the top cover 12 can be reduced compared tothe conventional technology, and the capacity of the outer tub can beincreased by virtue of the reduction of the distance.

The shock-absorbing unit 100, 200, 200′, 300 or 400 according to theabove-described embodiments may be provided in the casing in a pluralnumber. In this case, the shock-absorbing units 100, 200, 200′, 300 or400 may be symmetrically arranged with respect to the center of theinner tub 3, and in particular may be disposed at the four corners ofthe casing 10.

1. A laundry treatment apparatus comprising: a casing; an outer tubdisposed in the casing; a support rod connected at one end thereof tothe casing; an outer tub support part, which is moved along the supportrod and which supports the outer tub; at least one elastic memberfixedly disposed on the support rod so as to elastically support theouter tub support part from below; a first friction part disposed abovethe outer tub support part so as to create frictional force between thesupport rod and the first friction part; and a housing defining thereina space for accommodating the first friction part, the housing beingdisposed at a top of the outer tub support part and being moved alongwith the outer tub support part when the outer tub vibrates, and thehousing being independently moved alone when the outer tub support partis moved within a predetermined displacement range and being moved whilepushing the first friction part when the outer tub support part is movedbeyond the predetermined displacement range.
 2. The laundry treatmentapparatus according to claim 1, wherein the housing is removably coupledto the outer tub support part.
 3. The laundry treatment apparatusaccording to claim 2, wherein one of the housing and the outer tubsupport part is provided with a coupling protrusion, and the other ofthe housing and the outer tub support part is provided with a couplingloop with which the coupling protrusion engages.
 4. The laundrytreatment apparatus according to claim 3, wherein engagement between thecoupling protrusion and the coupling loop is achieved by relativerotation between the housing and the outer tub support part about thesupport rod.
 5. The laundry treatment apparatus according to claim 3,wherein the outer tub support part comprises: a neck, which has alongitudinal central hole through which the support rod passes and whichhas an upper end coupled to the housing; and a cap, which is provided ata lower end of the neck and is enlarged radially and outwardly, a lowerend of the cap being elastically supported by the elastic member and anupper end of the cap supporting the outer tub, and wherein the couplingprotrusion is formed on the cap.
 6. The laundry treatment apparatusaccording to claim 1, wherein one of the first friction part and thehousing includes a protrusion projecting from a predetermined surfacethereof, and a remaining one of the first friction part and the housingis in contact with the protrusion while the housing is moved.
 7. Thelaundry treatment apparatus according to claim 6, wherein the firstfriction part comprises: a soft frictional member for creatingfrictional force between the support rod and the frictional member, anda hard holder movable along the support rod and receiving therein thefrictional member, and wherein the protrusion is formed on the housing.8. The laundry treatment apparatus according to claim 1, wherein thehousing comprises: an upper wall portion defining an upper surface ofthe space; a lower wall portion defining a lower surface of the space;and a plurality of side wall portions connecting the upper wall portionto the lower wall portion and defining a side surface of the space, theplurality of side wall portions being arranged at predeterminedintervals, and a spacing between a pair of adjacent ones of theplurality of side wall portions being sized so as to allow the firstfriction part to pass therethrough.
 9. The laundry treatment apparatusaccording to claim 8, wherein at least one of the upper wall portion andthe lower wall portion includes a protrusion that the first frictionpart contacts while being moved.
 10. The laundry treatment apparatusaccording to claim 8, wherein each of the upper wall portion and thelower wall portion has therein a hole through which the support rodpasses.
 11. The laundry treatment apparatus according to claim 1,wherein the outer tub support part comprises: a neck, which has alongitudinal central hole through which the support rod passes and whichhas an upper end coupled to the housing; and a cap, which is provided ata lower end of the neck and is enlarged radially and outwardly, a lowerend of the cap being elastically supported by the elastic member and anupper end of the cap supporting the outer tub, and wherein the laundrytreatment apparatus further comprises a second friction part fixedlydisposed with respect to the cap, the second friction part alwayscreating frictional force between the support rod and the secondfriction part when the outer tub vibrates.
 12. The laundry treatmentapparatus according to claim 11, wherein the cap comprises: an upperwall portion supporting the outer tub; a lower wall portion spaced apartfrom the upper wall portion and elastically supported by the elasticmember; and a plurality of side wall portions connecting the upper wallportion to the lower wall portion, the plurality of side wall portionsbeing arranged at predetermined intervals, and a spacing between a pairof adjacent ones of the plurality of side wall portions being sized soas to allow the second friction part to pass therethrough.
 13. Thelaundry treatment apparatus according to claim 12, wherein the secondfriction part comprises: a soft frictional member fitted over thesupport rod, and a hard holder accommodating the frictional membertherein.
 14. The laundry treatment apparatus according to claim 1,wherein the at least one elastic member includes first and secondsprings, which are concentrically arranged.
 15. The laundry treatmentapparatus according to claim 14, wherein the second spring is compressedafter the first spring has been compressed to a predetermined extent bybeing pushed by the outer tub support part.
 16. The laundry treatmentapparatus according to claim 15, further comprising a movable member,which is disposed under the outer tub support part and is movable alongthe support rod, the movable member being elastically supported by thesecond spring, wherein the movable member is moved by the outer tubsupport part after the first spring has been compressed to apredetermined extent.
 17. The laundry treatment apparatus according toclaim 16, wherein the second spring is disposed inside the first spring.18. The laundry treatment apparatus according to claim 16, wherein thesupport rod includes a base provided at a remaining end thereof so as tosupport the first spring, wherein the base includes an annular partitionwall projecting from a surface thereof supporting the first spring, andwherein the partition wall is disposed inside the first spring, and thesecond spring is disposed inside the partition wall.
 19. The laundrytreatment apparatus according to claim 18, wherein at least one of thefirst and second springs is coupled to the base so as to preventrotation thereof about the support rod.
 20. The laundry treatmentapparatus according to claim 18, wherein the first and second springsare concentrically arranged when viewed in a transverse section.
 21. Thelaundry treatment apparatus according to claim 1, wherein the elasticmember has a modulus of elasticity that varies nonlinearly depending ona load.
 22. The laundry treatment apparatus according to claim 21,wherein the elastic member includes an irregular pitch spring, which hassections having mutually different pitches.
 23. The laundry treatmentapparatus according to claim 22, wherein the irregular pitch springincludes one section having a predetermined pitch and a predeterminedlength, and a pair of sections, which are disposed at opposite ends ofthe one section and having a pitch different from the one section, andwhich extend therefrom.
 24. The laundry treatment apparatus according toclaim 23, wherein among the sections, the one section has the greatestpitch.
 25. The laundry treatment apparatus according to claim 1, furthercomprising at least one magnet for creating an attractive forceattributable to a magnetic field between the first friction part and themovable part in a direction perpendicular to a direction in which thefirst friction part is displaced.
 26. The laundry treatment apparatusaccording to claim 25, wherein the magnet is provided at one of thefirst friction part and the housing, and a remaining one of the firstfriction part and the housing is provided with a material for creatingattractive force between the magnet and the material.
 27. The laundrytreatment apparatus according to claim 26, wherein the first frictionpart comprises: a soft frictional member for creating a frictional forcebetween the support rod and the frictional member, and a holder movablealong the support rod and receiving therein the frictional member,wherein the housing comprises: an upper wall portion for pushing thefirst friction part downward while the outer tub support part isdisplaced downward; a lower wall portion longitudinally spaced apartfrom the upper wall portion at a predetermined interval so as toaccommodate the first friction part therebetween; and a side wallportion connecting the upper wall portion to the lower wall portion, andwherein the holder is made of a material for creating attractive forcebetween the magnet and the material, and the magnet is spaced apart fromthe magnet and is disposed at the side wall portion.
 28. The laundrytreatment apparatus according to claim 27, wherein the magnet isdisposed outside the side wall portion.